1. Field of the Invention
The present invention relates to meter centers for electrical power distribution systems. Specifically, it relates to improvements in jumpers to assist in the removal of individual meters from the meter center without interrupting current flow.
2. Description of the Related Art
A typical meter center for metering electrical power delivered to multiple locations from a common system includes a plurality of meter compartments, with each meter compartment containing one meter corresponding to one location to which power is delivered. A supply bus, typically a three-phase bus having three line wires plus a neutral, extend from the feeder bus to the meter compartment. The feeder buses in turn extend from the utility power lines. Tenant buses connect to the meter compartment to the location wherein the electrical power is utilized. Both the supply buses and tenant buses are connected to a meter socket of the meter compartment, with the meter socket securing a meter providing an electrical connection between the supply buses and the tenant buses. This electrical connection is formed by single ended plug-in jaws on the meter socket, dimensioned and configured to engage corresponding stabs on the meter.
When a meter must be disconnected from the meter socket, it is desirable to provide continued electrical power to the location monitored by the meter. A typical meter socket provides a horn bypass adjacent to, and an electrical communication with, each plug-in jaw and its associated bus. The horn bypasses permit connection of a jumper from the horn bypass of the supply bus to the horn bypass of the tenant bus prior to removal of the meter from the meter socket. Some presently available jumper cables include a clamp at each end, with each clamp having a pair of jaws surrounded by insulation. Mating angled surfaces on the jaws and insulation cause the jaws to be drawn together when the insulation is rotated. However, presently available jumpers do not provide adequate clamping to the bypass horns, and also interfere with insertion and removal of the meter.
Accordingly, an improved jumper for connecting the supply bus with its corresponding tenant bus prior to removal of an electrical meter from its meter socket is desired.
The present invention is directed to an improved clamp for jumper cables for use with electrical meters. The clamp includes an electrically conductive stationary jaw, and an electrically conductive movable jaw. The opposing stationary and movable jaws are housed within an insulator sleeve. The stationary jaw and insulator sleeve define a channel therethrough, dimensioned and configured to receive a threaded rod. The threaded rod is threadedly engaged to the movable jaw at one end, and includes a knob at its opposite end. The stationary jaw and movable jaw define corresponding angled surfaces, so that turning the threaded rod to extend or retract the movable jaw will move the movable jaw parallel to these angled surfaces, thereby causing the jaw to move between an open position and a closed position. The channel containing the threaded rod is sufficiently large relative to the threaded rod to permit lateral movement of the rod, corresponding to the inward and outward movement of the movable jaw.
A jumper cable includes a clamp of the present invention at either end, permitting the jumper cable to be connected between a supply bus and its corresponding tenant bus within the socket for an electrical meter, by securing each clamp to the bypass horn corresponding to each bus. A typical socket for an electrical meter includes two supply buses, and two tenant buses, although the present invention is not limited to this number of corresponding supply and tenant buses. While the meter is in use, the meter forms and electrical connection between each supply bus and its corresponding tenant bus, thereby completing the current path from the utility lines, through the feeder bus, the supply bus, the meter, and the tenant bus, and finally to the consumer. This electrical connection is formed by single-ended plug-in jaws on the meter socket, with each plug-in jaw corresponding to one bus, and a stab on the meter corresponding to each jaw.
To remove an individual meter from its socket, one end of a jumper cable is first clamped to the bypass horn corresponding to one of the buses (which may be either a supply bus or a tenant bus), and the knob is turned to move the movable jaw from its open position to its closed position, thereby securing the bypass horn between the movable jaw and the fixed jaw. The opposite end of the jumper cable is likewise clamped to the corresponding bus. The procedure is repeated until a jumper cable connects each supply bus within the socket to its corresponding tenant bus. The meter may then be removed from the socket, with the stabs in the meter exiting the jaws. The electrical current which previously flowed from the supply buses, through the meter, to the tenant buses will now flow from the supply buses, through the jumper cables, to the tenant buses, until servicing of the meter is complete, and the meter is reattached to the socket. At this point, the jumper cables are removed from the socket.
A clamp of the present invention is particularly advantageous for making electrical connections because the inner clamping surfaces of the stationary and moveable jaws remain parallel to each other as the moveable jaw is moved. This maximizes the surface area contact between each jaw of the clamp and the bypass horn, maximizing the security of the clamp and minimizing electrical resistance in the connection between the clamp and bypass horn.
It is therefore an aspect of the present invention to provide a jumper cable for use with electrical meter sockets, having a clamp at each end providing secure clamping to the bypass horns within the meter socket.
It is another aspect of the present invention to provide a jumper cable for use with electrical meter sockets, wherein the clamps at each end of the jumper cable do not interfere with installation and removal of the electrical meter from the socket.
It is a further aspect of the present invention to provide a jumper cable for use with electrical meter sockets, wherein electrical resistance within the connection between the clamping jaws and bypass horn is minimized.
It is another object of the present invention to provide a jumper cable for use with electrical meter sockets, wherein the jaws of the cable""s clamps remain parallel throughout movement between their open and closed positions.
These and other aspects of the invention will become apparent through the following description and drawings.